'Unlocking the Case' printed from http://nrich.maths.org/

Asma and Atif were sorting through some things that had been brought in for the school jumble sale when they found an old case with a combination lock on it.

They had no idea what was in it but it was quite heavy and they wanted to find out what was inside. The only clue they had was a sticker next to the lock which said T16 and that there were three digits to find. What did the code mean? What was the combination that unlocked the case?